I'll look at reseating with new thermal paste next.For the system to restart under any GPU load would indicate to me either power supply and/or graphics card related issues. I’d definitely clean and redo the thermal paste as mentioned by @eidairaman1
When you are in the BIOS next, please get a picture of the systems voltages if you can.
Photos of the bios page attached.
Memtest86 completed and passed (XMP disabled)Run memtest86 on your system to find out if memory is unstable.
Can you provide us the complete system specs (cpu, ram, motherboard)
It wasn't disabled, but it is now. Next time it crashes, I'll post the blue screen.Have you disabled Automatically Restart option under Startup and Recovery / System Failure?